Vehicle body frame of motorcycles

ABSTRACT

There is provided a vehicle frame structure for a motorcycle having an appealing appearance, which structure can be assembled lightweight and compact in size and at a reduced cost. The vehicle frame structure includes a head block ( 2 ) including a head tube ( 3 ), a main frame ( 11 ) forked leftwards and rightwards from the head block ( 2 ) to form a pair of main frame half portions ( 11   a,    11   b ) extending rearwardly thereof, and swing arm brackets ( 8 ) extending downwardly from rear ends of the main frame half portions ( 11   a,    11   b ). An inner frame portion ( 21 ) of the main frame ( 11 ) and the swing arm brackets ( 8 ) in their entirety or respective inner portions of the swing arm brackets ( 8 ) are integrally formed by an inner member ( 19 ) prepared from a metal casting, and at least an outer frame portion of the main frame ( 11 ) is formed by an outer member ( 20 ) prepared from a sheet metal.

FIELD OF THE INVENTION

The present invention relates to a vehicle frame structure for amotorcycle, which includes main frames prepared from a sheet metal and acast metal.

BACKGROUND ART

For a well-known vehicle frame structure of a motorcycle, the JapanesePatent No. 2688916 discloses a vehicle frame structure which includes apair of left and right main frame pieces each having inner and outerplates prepared from a sheet metal and also includes rear arm brackets(swing arm brackets) connected to and extending downwardly from acorresponding rear end of the main frame pieces and having left andright bracket bodies prepared from a cast metal, the left and rightbracket bodies being connected with each other by means of cross tubes.

However, since in this known vehicle frame structure the inner and outerplates forming the pair of the left and right main frame pieces are eachprepared from a sheet metal, it is difficult to secure dimensionalaccuracy. Because of this, where an air cleaner is desired to bedisposed inside the main frame pieces forming a forked main frame, it isnecessary to set a clearance for the mounting of the air cleaner andother components with a dimensional error taken into consideration. As aresult, the main frame tends to become bulky in size, resulting in aweight increase.

Also, as shown in FIG. 4 c, when an outer plate 61 and an inner plate 62forming the main frame and prepared from a sheet metal are weldedtogether, the outer and inner plates are overlapped one above the otherand then connected together by a fillet welding. Accordingly, in view ofthe facts that the shape of a welding groove is limited and that it isdifficult to position the outer and inner plates 61 and 62, both ofwhich are prepared from a sheet metal and are therefore difficult to beprepared with dimensional accuracy, so as to be overlapped one above theother with no gap formed between the outer and inner plates 61 and 62,the welding workability tends to be lowered. Also, since respectiveportions in contact with welding joints between the outer and innerplates 61 and 62, which are encompassed by the phantom circles 63 inFIG. 4 c, tends to be melted during the fillet welding, a welding torchmust be set and held relative to the plate surface at an angle effectiveto accomplish an optimum welding and, therefore, not only does thewelding require time-consuming and cumbersome procedures, but it alsorequires the skill. In addition, since the welding joint has a step atwhich the cross-sectional area varies greatly, stress concentrationtends to set up easily.

Since the main frame is prepared by welding the outer frame 61 and theinner frame 62, each prepared from the sheet metal, finished productsare apt to have large dimensional variations. Accordingly, when the aircleaner is to be disposed in a space inside the main frame, a joint ofan air guide port inside the main frame and a joint of the air cleanerwill not be smoothly positioned relative to each other, resulting incomplicated and time-consuming assemblage.

Yet, when the strength of the main frame prepared from the sheet metalis desired to be locally reinforced, the main frame in its entirety hasto be prepared to have an increased thickness and/or a separate elementsuch as a gusset plate must be welded to the area required to bereinforced, resulting in increase of the weight and the manufacturingcost.

DISCLOSURE OF THE INVENTION

The present invention has been devised in view of the foregoing problemsand is intended to provide a vehicle frame structure for a motorcyclehaving an appealing appearance, which structure can be assembledlightweight and compact in size and at a reduced cost.

In order to accomplish the foregoing object, the vehicle frame structurefor a motorcycle according to the present invention includes a headblock including a head tube, a main frame forked leftwards andrightwards from the head block to form a pair of left and right mainframe half portions extending rearwardly of the head block, and swingarm brackets extending downwardly from rear ends of the main frame halfportions. An inner frame portion of the main frame and the swing armbrackets in their entirety or inner portions of the swing arm bracketsare integrally formed by an inner member prepared from a metal casting.On the other hand, at least an outer frame portion of the main frame isformed by an outer member prepared from a sheet metal.

In this vehicle frame structure for a motorcycle, since the outerportion of the main frame is formed by the outer member prepared from asheet metal, not only can an excellent appearance be obtained ascompared with a metal casting, but a weight reduction can also beachieved. On the other hand, since the inner portion of the main frameis formed by the inner member prepared from a metal casting that can bemanufactured to have an accurate shape with higher dimensional precisionthan that afforded by a sheet metal, the following advantages can beobtained. Specifically, since the clearance for component parts such asan air cleaner that are to be disposed inside the forked main frame canbe set to a value as small as possible, the widthwise dimension of themain frame can be reduced to facilitate compactization and reduction inthe weight of the main frame. Also, when the outer member and the innermember are welded with each other, a welding step can be integrallyformed in the inner member prepared from a metal casting, with each oftip portions of the inner member formed as a thin-walled portion and,accordingly, if the outer member prepared from a sheet metal isoverlapped with this thin-walled portion so as to be butted against thewelding step to perform a butt welding, positioning at the welding sitecan be accomplished easily and a favorable welding can be carried out.Also, since the shape of a welding groove between the inner member andthe outer member, that is, the shape of a weld joint can have thefreedom, the weldability can be increased to facilitate the efficientwelding. In other words, the time required to accomplish the welding canbe shortened.

Moreover, when the butt welding is performed, since a smooth weld jointwithout accompanying a bead protrusion can be obtained and, also, sincethe cross-sectional area of the resultant weld is uniform without beingaccompanied by any stress concentration, strength variations of the mainframe can be withheld at a low level and, as a result, the weight of themain frame can be reduced. Also, since the inner member prepared from ametal casting and forming the inner portion of the main frame can beeasily formed integrally with holding elements for an air cleaner and/oran electrical component and damping ribs if necessary, as compared withthe conventional arrangement in which separate and independent retainerbrackets are welded or bolted to a main frame or in which a dampingstructure having a rubber damper embedded in a main frame is employed,the number of component parts can be reduced to thereby reduce the cost.In addition, where the strength of the main frame is desired to belocally enhanced, it can be accomplished merely by increasing thethickness of that portion of the inner member, formed by casting, whichrequires reinforcement.

In a preferred embodiment of the present invention, a guide passage forintroduction of an air to an air cleaner of an engine is formed insidethe main frame. According to this feature, since the inside of the mainframe functions as a part of the air cleaner, a cleaner casing for theair cleaner can be formed compact in size. In such case, since the innerportion of the main frame with respect to the vehicle frame structure isformed by the inner member prepared from a metal casting and capable ofbeing manufactured with higher dimensional accuracy than that affordedby a sheet metal, the guide passage and a front portion of the cleanercasing can be favorably connected with each other to enhance theassemblability when the air cleaner or the like is disposed inside theforked main frame.

The air cleaner may be positioned within a space delimited between apair of left and right main frame half portions of the main frame.According to this feature, the space between the main frame halfportions can be effectively utilized.

Also, the inner and outer frame portions of the main frame may beconfigured to represent a generally U-shape with their openings jointedwith each other to define the guide passage therein. According to thisfeature, the space for the guide passage can be secured.

In another preferred embodiment of the present invention, a flashingplate is employed for deflecting the flow of the air to separate watercontained in the air is disposed within the guide passage. According tothis feature, even though the air introduced contains raindrops or thelike, intrusion of those raindrops into a downstream portion of acleaner element of the air cleaner can be avoided by the flashing plate.Also, since the flashing plate can be easily formed integrally with theinner member that is prepared from a metal casting, there is no increasein the number of component parts and the cost.

In a further preferred embodiment of the present invention, the headblock is formed with an intake passage through which the air is suckedand supplied to the guide passage. According to this construction, thespace available within the frame structure from the head block towardsthe main frame can be utilized effectively to allow the air to beefficiently supplied to the air cleaner.

Also, the inner member is preferably integrally cast with cross membersfor connecting the pair of the left and right main frame half portionswith each other. According to this feature, the rigidity of the mainframe can be increased.

In addition, the inner member can be integrally cast with damping ribs.According to this feature, vibration of the main frame can besuppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a motorcycle having a vehicle frame structureaccording to a preferred embodiment of the present invention;

FIG. 2 is a view of the vehicle frame structure as viewed in a directionII shown in FIG. 3;

FIG. 3 is a side view showing the vehicle frame structure supporting anengine;

FIG. 4 a is an enlarged cross-sectional view of the vehicle framestructure taken along the line IV-IV in FIG. 2;

FIG. 4 b is a fragmentary enlarged view of FIG. 4 a; and

FIG. 4 c is a sectional view of the conventional vehicle framestructure, shown for comparison purpose, showing the manner in whichinner and outer plates of a main frame of the conventional vehicle framestructure are welded together.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a motorcycle having a vehicle frame structureaccording to a preferred embodiment of the present invention. Themotorcycle includes a vehicle frame structure 1 and a front fork 4. Thevehicle frame structure 1 has a head tube 3 formed integrally with ahead block 2 at a front end of the vehicle frame structure 1 and alsohas swing arm brackets 8 positioned below a generally intermediateportion of the vehicle frame structure 1 to pivotally support a swingarm 9 for movement up and down with a rear wheel 10 rotatably carried bythe swing arm 9. The front fork 4 is rotatably supported by the headtube 3 through a steering shaft (not shown) with a front wheel 7rotatably carried by the front fork 4. An internal combustion engine Eis mounted on the vehicle frame structure 1 at a location below agenerally intermediate portion thereof and is used to drive the rearwheel 10 by a chain (not shown) while the motorcycle can be steeredthrough the steering shaft and a handlebar 12 fixed on an upper end ofthe front fork 4. A fuel tank 13 is mounted on the top of main frames 11of the vehicle frame structure 1.

A seat rail 14 and a reinforcement rail 14A cooperating together todefine a rear portion of the vehicle frame structure 1 are secured to arear portion of the main frame 11, with a seat 17 for supporting amotorcyclist mounted on the seat rail 17. A single rear suspension 18 isinterposed between the vehicle frame structure 1 and the swing arm 9.

FIG. 2 illustrates the vehicle frame structure 1 as viewed in adirection II shown in FIG. 3. The illustrated vehicle frame structure 1includes the main frame 11 forked from the head block 2 so as to extendrearwardly (or downwardly as viewed in FIG. 2) therefrom on left andright sides, respectively, to form a pair of left and right main framehalf portions 11 a and 11 b, and also includes the swing arm brackets 8that extend downwardly from left and right rear ends of the main frame11, respectively, as shown in FIG. 3. The main frame 11 includes, asshown in FIG. 2, an inner member 19, prepared from a cast metal, and anouter member 20 prepared from a sheet metal and joined to the innermember 19. The inner member 19 includes an inner frame portion 21, madeup of a pair of left and right inner frame halves 21A and 21B that arepositioned inside the vehicle frame structure, and the swing armbrackets 8, the inner frame portion 21 and the swing arm brackets 8being integrated together by a metal casting technique. The outer member20 includes a pair of left and right outer frame halves 20A and 20B thatare prepared from a sheet metal and define an outer frame portion of themain frame 11 of the vehicle frame structure 1.

FIG. 4 a illustrates an enlarged cross-sectional view taken along lineIV-IV in FIG. 2. As shown therein, the pair of the left and right outerframe halves 20A and 20B of the outer member 20 and the pair of the leftand right inner frame halves 21A and 21B of the inner frame portion 21of the inner member 19 are each in the form of U-sectionedconfiguration. The pair of the left and right outer frame halves 20A and20B and the pair of the left and right inner frame halves 21A and 21Bare welded together at their respective openings to define the mainframe 11. A guide passage 22 for an air A (FIG. 1) forming a part of anupstream side of an air cleaner 28 is defined inside the pair of theleft and right main frame half portions 11 a and 11 b. It is to be notedthat the details of the route of flow of the air A and the welding ofthe outer frame halves 20A and 20B and the inner frame halves 21A and21B will be described later.

The route of flow of the air A will now be described. Referring to FIG.2, the head block 2 is a metal casting product made up of an air intakeduct 23 having its front end opening outwardly and the head tube 3, bothof which are molded integrally with each other, with a rear end of theair intake duct 23 welded to a front end of the main frame 11. Thewelding line is indicated by a symbol L1. Accordingly, the air Aintroduced into intake passages 23 b through an intake port 23 a at thefront end of the intake duct 23 is introduced being branched into leftand right introducing passages 22 in the main frames 11. Also, as shownin FIGS. 1 and 2, the front end of the intake duct 23 is fluid-connectedwith an air introducing duct 27 opening at a front surface of a frontfairlng 24 of the motorcycle, and the air A is thus introduced from thisair introducing duct 27 into the intake duct 23.

Within an inner space of the forked main frame 11 shown in FIG. 2, thatis, an inner space between the two main frame half portions 11 a and 11b, a cleaner casing 31 accommodating therein an cleaner element 29forming a part of the air cleaner 28 is disposed, and an upstream sideof the cleaner element 29 within the cleaner casing 31 is coupled influid-communication with the left and right introducing passages 22 inthe main frame 11 through a pair of left and right connecting ducts 32.The cleaner casing 31 is supported by a throttle body 25 shown in FIG.3.

As shown in FIGS. 1 and 2, the cleaner casing 31 is connected with aplurality of ducts 33 a of fuel supply devices 33 that are connectedwith respective cylinders of the multi-cylinder engine E. Accordingly,the air A after having been branched and flowed from the air introducingduct 27, shown in FIG. 1, into the left and right introducing passages22 in the main frames 11 and the connecting ducts 32 through the intakepassages 23 b of the air intake duct 23 is supplied to the cleanercasing 31 and is then purified by the cleaner element 29. The purifiedair is supplied from a purified air chamber 30 at a downstream side ofthe cleaner element 29 to the fuel supply device 33 through the ducts 33a and is finally supplied to the engine E after having been mixed with afuel in the fuel supply devices 33.

In the vehicle frame structure 1, since the introducing passages 22 inthe main frame 11 functions as a part of the air cleaner 28 to carryout, for example, noise reduction as a silencer and waterproofing, thecleaner casing 31 of the air cleaner 28 can be compact in size. In suchcase, since the inner space of the main frame 11 is defined by the innermember 19 prepared by the metal casting capable which enables to providethe inner member 19 with higher dimensional accuracy than the sheetmetal, a consistent connection between the introducing passage 22 andthe front portion of the air cleaner 28 can be achieved through theconnecting duct 32 and the assemblability can be increased when the aircleaner 28 is disposed within the inner space of the forked main frame11. Also, since the intake passages 23 b are defined in the air intakeduct 23 of the head block 2, the space available from the head block 2towards the main frame 11 can be effectively utilized to allow the air Ato be efficiently supplied to the air cleaner 28.

Also, in this embodiment, a flashing plate 34 for deflecting the flow ofthe air A over 270° to separate water contained in the air A ispositioned within each of the left and right introducing passages 22 ofthe main frame 11 at a location upstream of the mounting site of theconnecting duct 32. This flashing plate 34 is formed integrally witheach of the left and right inner frame halves 21A and 21B of the innerframe portion 21 by a metal casting technique. Accordingly, even thoughthe air A introduced contains raindrops or the like, intrusion of thoseraindrops into the air cleaner 28 can be avoided by the flashing plates34. Also, since each of the flashing plates 34 can be easily formedintegrally with the inner frame portion 21 prepared from a metalcasting, there is no increase in the number of component parts used andthe cost will not be increased.

The inner frame halves 21A and 21B forming the inner portions of themain frame half portions 11 a and 11 b and the left and right swing armbrackets 8 and 8 are connected with each other by respective crossmembers 37 and 38 extending left and right therebetween and formedintegrally with the inner member 19 by a metal casting technique.Accordingly, the rigidity of the main frame 11 can be increased. Thefront upper cross member 37 is positioned rearwardly of the cleanercasing 31. Accordingly, the space for accommodating the cleaner casing31 is delimited by the left and right main frame half portions 11 a and11 b and the upper cross member 37. As shown in FIG. 3, at a locationsubstantially intermediate of the vertical direction of the crossmembers 37 and 38, fitting holes 39 are defined in the swing armbrackets 8 to bear the swing arm 9 shown in FIG. 1.

A pair of left and right first engine mounts 40 for supporting an upperportion of the engine E are formed integrally with the main frame 11 soas to protrude downwardly therefrom. On the other hand, a portion of thecylinder of the engine E confronting each of the first engine mounts 40is formed integrally with a fitting piece 43 so as to protrudetherefrom. The first engine mounts 40 and the fitting pieces 43 areoverlapped one above the other with spacers (not shown) interveningtherebetween and, by fastening bolts 44, inserted into respectivefitting holes of the first engine mounts 40 and the fitting pieces 43,with nuts (not shown), the engine E is supported at its front upperportion by the main frames 11.

Also, a pair of left and right second engine mounts 47 for supporting arear upper portion of the engine E are formed integrally with the uppercross member 37 in the main frame 11 so as to protrude forwardlytherefrom. On the other hand, a portion of a crankcase 48 of the engineE confronting each of the second engine mounts 47 is formed integrallywith a fitting piece 49 so as to protrude therefrom. The second enginemounts 47 and the fitting pieces 49 are overlapped one above the otherwith their fitting holes (not shown) aligned and, by fastening bolts44A, inserted into the fitting holes, with nuts (nut shown), the engineE is supported at its rear upper portion by the main frames 11.

In addition, a pair of left and right third engine mounts 50 forsupporting a lower portion of the engine E are formed integrally withthe lower cross member 38 in the swing arm brackets 8 so as to protrudeupwardly therefrom. On the other hand, another portion of the crankcase48 of the engine E confronting each of the third engine mounts 50 isformed with a screw hole (not shown). Yet, the swing arm brackets 8 areformed with respective throughholes 51 for a bolt fastening work. Thus,by aligning the fitting holes (not shown) in the third engine mounts 50and the screw holes in the engine E with each other and then insertingfitting bolts 44B into the screw holes through the throughholes 51, theengine E is supported at its lower portion by the swing arm brackets 8.

Since the first to third engine mounts 40, 47 and 50 are formedintegrally with the inner member 19, as compared with the conventionalarrangement in which the engine is mounted through engine mounts whichare formed by separate and independent elements, the number of componentparts can be reduced and the assemblability can be increased. Inaddition, the engine E can be stably supported by the first to thirdengine mounts 40, 47 and 50 that are formed integrally with the innermember 19 prepared from a metal casting and thus having a high rigidity.

It is to be noted that the inner member 19 of a metal casting can beformed integrally with other members than the first to third enginemounts 40, 47 and 50. In the illustrated embodiment, in order for theseat rail 14 and the reinforcement member 14A shown in FIG. 1 to befitted, a pair of left and right support pieces 52 and a pair of leftand right support pieces 53 shown in FIG. 2 are formed integrally withthe upper cross member 37 and inner surfaces of the swing arm brackets8, respectively. Also, a plurality of damping ribs 56 are formedintegrally with an inner surface of each of the left and right innerplate halves 21A and 21B of the inner member 19. Where the damping ribs56 are provided integrally, as compared with the conventional dampingstructure in which rubber dampers are embedded within a main frame, thenumber of component parts can be reduced to achieve reduction in cost.Yet, the inner member 19 can be provided integrally with, for example, amounting bracket 54 for holding an electrical component 41 as shown bythe double-dotted line in FIG. 2. In addition, as shown in FIG. 3, arear end portion of each of the inner frame halves 21A and 21B of theinner frame portions 21 is provided with a drain port 57 openinginwardly for discharging a water component, trapped by the flashingplate 34 (FIG. 2), to the outside of the vehicle frame structure 1.

In the next place, the welding between the outer frame halves 20A and20B of the outer member 20 and the inner frame halves 21A and 21B of theinner member 19 will be described with reference to FIG. 4 b whichillustrates an important portion of FIG. 4 a on an enlarged scale. Upperand lower end portions of each of the inner frame halves 21A and 21B ofthe inner members 19 of a metal casting are formed with welding steps 58each corresponding to the thickness of each of the outer frame halves20A and 20B of the outer member 20, with their tip portions defining athin-walled portion 59. Opposite end portions of each of the outer framehalves 20A and 20B of the outer member 20 of a sheet metal areoverlapped over the corresponding thin-walled portions 59 and a buttwelding 60 is carried out while the opposite end portions of each of theouter frame halves 20A and 20B butt against the associated welding steps58.

The employment of the above described welding method is effective tofacilitate an accurate positioning of the outer frame halves 20A and 20Band the inner frame halves 21A and 21B relative to each other at thesite of welding and is also effective to provide a high degree offreedom on the shape of the grooves between the inner frame halves 21Aand 21B and the outer frame halves 20A and 20B. Accordingly, theweldability can be considerably increased and no high welding skill isneeded to achieve the intended welding. In addition, where a buttwelding is performed, if a suitable groove angle θ is selected, a merelinear movement of a welding torch while it is held at right angles tothe welding groove is effective to secure penetration of an equal depthin both the outer frame halves 20A and 20B and the inner frame halves21A and 21B so that smooth weld joints 60 without accompanying a beadprotrusion can be obtained. Also, since the cross-sectional area of theresultant weld is uniform enough to prevent any stress concentration,the margin of the frame structure strength with respect to the weldjoints 60 can be withheld at a low level. As a result, the weight of themain frame 11 can be reduced.

Also, since the inside of the main frame 11 is delimited by the outermember 20 of a sheet metal, the vehicle frame structure 1 can provide anappealing appearance. In addition, since the inside of the main frame 11is constructed of the inner member 19 of a metal casting that canexhibit higher dimensional accuracy than a sheet metal, the clearancefor the cleaner casing 31 or other components positioned inside theforked main frame 11 can be minimized to a value as small as possibleand, accordingly, the widthwise dimension of the main frame 11 can bereduced to facilitate reduction in size and weight.

It is to be noted that although in the foregoing embodiment the innerframe portion 21 of the inner member 19 has been described as comprisedof the pair of left and right inner frame halves 21A and 21B, the innermember 19 may be of a structure including an inner frame portion havingleft and right inner frame halves formed integrally and swing armbrackets. Also, although in the foregoing embodiment the outer member 20has been shown as forming an outer frame portion of the main frame 11,the outer member 20 may form respective outer portions of the main frame11 and the swing arm brackets 8. In such case, the inner member 19 willform the inner portions of the swing arm brackets 8.

1. A vehicle frame structure for a motorcycle, which comprises a headblock including a head tube, a main frame forked leftwards andrightwards from the head block to form a pair of left and right mainframe half portions extending rearwardly thereof, and swing arm bracketsextending downwardly from rear ends of the main frame half portions;wherein an inner frame portion of the main frame positioned inside thevehicle frame structure and the swing arm brackets in their entirety orrespective inner portions of the swing arm brackets are integrallyformed by an inner member prepared from a metal casting, and wherein atleast an outer frame portion of the main frame is formed by an outermember prepared from a sheet metal:
 2. The vehicle frame structure forthe motorcycle as claimed in claim 1, wherein a guide passage forintroduction of an air to an air cleaner of an engine is formed insidethe main frame.
 3. The vehicle frame structure for the motorcycle asclaimed in claim 2, wherein the air cleaner is positioned within a spacedelimited between the pair of the left and right main frame halfportions of the main frame.
 4. The vehicle frame structure for themotorcycle as claimed in claim 2, wherein the inner and outer frameportions of the main frame are configured to represent a generallyU-shape, with their openings jointed with each other to define the guidepassage therein.
 5. The vehicle frame structure for the motorcycle asclaimed in claim 2, wherein a flashing plate for deflecting the flow ofthe air to separate water contained in the air is disposed within theguide passage.
 6. The vehicle frame structure for the motorcycle asclaimed in claim 2, wherein the head block is formed with an intakepassage through which the air is sucked and supplied to the guidepassage.
 7. The vehicle frame structure for the motorcycle as claimed inclaim 6, wherein the head block is a metal casting including an airintake duct that defines the intake passage and the head tube, and iswelded to the main frame.
 8. The vehicle frame structure for themotorcycle as claimed in claim 1, wherein the inner member is integrallycast with a cross member for connecting the pair of the left and rightmain frame half portions with each other.
 9. The vehicle frame structurefor the motorcycle as claimed in claim 1, wherein the inner member isintegrally cast with damping ribs.
 10. A combination vehicle framestructure for a motorcycle and air cleaner for providing air to anengine, comprising: a hollow frame body member extending to the front ofthe motorcycle with an opening for receiving an air flow pressurized byforward movement of the motorcycle and a guide passage connected to theopening for directing air; an air cleaner positioned downstream of theopening and configured to fit within the hollow frame body member forcommunication with the guide passage for cleaning the air and with theengine for delivering clean air; and a flashing plate positioned withinthe guide passage traverse to the air flow for deflecting the flow ofthe air to separate water contained in the air.
 11. The combinationvehicle frame structure of claim 10 wherein the hollow frame body memberincludes a left and right main frame half portion and the air cleaner ispositioned within a space delimited between the pair of the left andright main frame half portions each of which support a guide passage anda traverse flashing plate adjacent openings to the air cleaner.
 12. Thecombination vehicle frame structure of claim 11 further including meansfor releasing any separate water from the hollow frame body member.